Permanent magnet blowout for electric switches



K. HEINRICH PERMANENT MAGNET BLOWOUT FOR ELECTRIC SWITCHES 2 Sheets-Sheet 1 Oct. 19, 1943.

Filed Jan. 13, 1941 O O O O 0 1 if 8 "Nu m. 5 HHHHIHH 2 I K) 7 KW 7 z 572 O %10 j g I WON/PHD f/f/A/R/CH BY- wzm 7/ G ATTORNEY.

K. HEINRICH 2,332,446

PERMANENT MAGNET BLOWOUT FOR ELECTRIC SWITCHES Oct 19, 1943 Filed Jan. 13, 1941 2 Sheets-Sheet 2 INVENTOR.

F UN; 0/ MOVEMENT Munhmm ATTORNEY.

Patented Oct. 19, 1943 PERMANENT MAGNET BLOWOUT FOR ELECTRIC SWITCHES Konrad Heinrich, Milwaukee, Wis., assignor to Allen-Bradley Company, Milwaukee, Wis., a corporation of Wisconsin Application January 13, 1941, Serial No. 374,175

3 Claims.

This invention relates to an improved permadent magnet blowout for electric Switches and particularly to a permanent magnet blowout suitable for use in a multiple break straight line motion switch of the enclosed arc chamber type.

The object of this invention is to secure an arrangement for a magnetic blowout associated with switch contacts operating in an arc chamber whereby the blowout force is so directed that the arcs occurring between contacts are effectively. directed away from the contacts and toward a side wall of the arc chamber regardless of the direction of flow of current through th contacts or the polarity of the blowout.

A further object is to secure a new structural arrangement for a magnetic blowout whereby blowout action is secured for a plurality of switch contacts by the use of a single blowout.

A further object is to secure improved blowout action in a multiple break straight line motion switch of the enclosed are chamber type by the use of a single permanent magnet uniquely positioned and proportioned to effectively increase the disrupting capacity of the switch.

A further object is to secure improved blowout action in a multiple break straight line motion switch of the enclosed arc chamber type by the use of a unique bar magnet having like poles at each end and a common pole in the center.

The trend of design in industrial electric control switches is toward small compact structures. Multiple break switches operating in an arc-resisting enclosure have been designed to meet the demand for compactnessand high interrupting capacity. This design has been utilized in the straight-line motion switch to great advantage. Any change in the design of a switch that in-= crease the interrupting capacity without increasing the size of the switch are of material value if the change does not entail an excessive additional cost. The blowout magnet structure disclosed in this invention materially increases the safe interrupting capacity of the switch.

The invention discloses a simple structural arrangement for a permanent magnet blowout in which the magnet is spaced within the are resisting enclosure so as to eiiectively increase the interrupting capacity of the switch. In a twopole double break switch this change is accomplished in the preferred form disclosed by three simple changes in structure. A recess is formed in the are enclosure for the blowout magnet, the locking bolt for the arc enclosure is changed from steel to brass and a permanent bar magnet is provided to secure blowout action. This single Figure 1 is a front view of the preferred switch structure showing the location of switch contacts, are resisting enclosure and blowout magnet with portions of the arc resisting enclosure in section to show the structural relation of the parts;

Figure 2 is a.sectional view taken along the lines 2-2 in Figure l; y

Figure 3 is a perspective view showing the principal elements of this invention with the outline of the arc enclosure shown in a phantom view by means of broken lines;

Figure 4 is a diagrammatic view showing the location of the contacts, are chamber, blowout magnet and the resulting magnetic field set up by the blowout magnet with the direction oi. the blowout action designated by means of arrows; and

Figure 5 is a diagrammatic view, similar to that shown in Figure 4, in which an alternate form of blowout magnet is used.

In the specific example disclosed as illustrative described in Patent No. 2,071,149 issued to Gustav O. Wilms et al.', February 16, 1937. The construction of the are hood 2 as shown in Figures 1 and 2 comprises a back section 3, front section 4 and top section 5 that interfit to form two restricted arc chambers Ill. The back section 3 is mounted to a supporting plate I by means of screws I and brass bolt 6. The brass bolt 6 also serves as a means to lock together the back section 3, front section 4 and top section 5 and as a retaining means for the blowout magnet 9. Four stationmy contacts 12 are mounted on top section 5 whereby two stationary contacts :2 are spaced within each of the two restricted arc chambers in as shown in Figure 2. In the bottom of each arc chamber Hi there is an opening ll for the bridging contact actuator I7 clearly shown in Figure 3.

The complete actuator assembly I9 comprising cross bar It, two bridging contact carriers I1 and two bridging contacts 13 is movable along the "line of movement designated in Figure 3. Each bridging contact carrier I1 is attached to cross bar l5 and the free end or each bridging contact carrier l1 supports a bridging contact l3. Each bridging contact l3 includes two contacts I4 that cooperate upon movement of the actuator assembly l9 to the closed position to engage the oppositely positioned stationary contacts I2.

Elie top section 5 of the arc hood enclosure 2 is formed with a recess 8 spaced midway between each pair of stationary contacts l 2. Into this 'recess there is inserted a permanent magnet 9, which in the assembled structure, is maintained in the recess by the brass bolt 6. The permanent magnet 9 used in this structure is of the "Alnico type which has been found to be very efllcient for this purpose.

The complete structural arrangement 01 the principal elements essential to this invention are clearly shown in Figure 3 which shows by means of a perspective view the arrangement of the stationary contacts I2,'permanent magnet blowout 9 and cooperating movable contacts l4. These are shown in solid line with the arc resisting enclosure 2 and openings Ii shown in a phantom view by broken lines. The exact structuraldetail of the actuator assembly I 9 and its assembled parts are not described in this specification. These details of construction do not constitute a part of the patentable subject matter of this application.

To further explain the blowout action resulting from the structure disclosed, a diagrammatic view showing the location of each pair oi stationary contacts l2 in each of the restricted arc chambers I and blowout magnet 9 is shown in Figure 4. The two stationary contacts l2 designated Line represent the incoming direct current lines marked plus and minus and the two stationary contacts [2 designated "Load show the outgoing side of the direct current lines marked minus and plus. Spaced midway between each pair of stationary contacts I 2 and midway between the restricted arc chambers I0 is a blowout magnet 9 having at one extremity a north pole and at the opposite extremity a south pole. The four stationary contacts l2 and bar magnet 9 be substantially in the same plane and there is designated in thi diagram the magnetic field resulting from the blowout magnet 9. The field in this plane common to both the stationary contacts l2 and the bar magnet 9 is herein designated as a magnetic plane. With the current flowing through the contacts in the direction indicated by means of the plus and minus signs as given in Figure 4 and with the blowout magnet 9 located in the designated position, the force effective to distend the arcs that occur upon interruption of an electric current is in the direction indicated by means of arrows. shown on the diagram. At each contact the arc is distended in a direction substantially at right angles to the line of motion of the switch and to impinge upon a wall of the arc chamber.

In order to cause the arc to more directly impinge upon the side wall of the arc chamber l0, it is found desirable to utilize a bar magnet having a length equal to or greater than the spacing of the contacts. The use of an excessive length is impractical because it is impossible to totally enclose the bar magnet in the arc resisting enclosure without increasihg the size thereof. It has also been found to be quit advantageous to use a modified bar magnet such as that shown in a similar diagram given in Figure where the contact member is perpendicular to a magnetic ,arcs are distended with a magnet of this type AS blowout is a permanent magnet. Compact switch bar magnet It has extreme poles or like polarity with a common pole in the center 01' the bar magnet as shown in Figure 5. By using a bar magnet it of this construction, herein designated as a three pole magnet, it is possible to have the arc impinge almost directly upon the side wall 01' the arc chamber. The direction in which the designated in Figure 5 by means of arrows.

The magnetic axis of the magnet as shown in Fig. 4 extends'between its polar faces, namely N and S and corresponds substantially to the length oi! the magnet. The magnetic axis of the magnet as shown in Fig. 5 extends between its polar faces, namely N and N and corresponds substantially to the length of the magnet.

In either oi. the two forms shown in Figures 4 and 5 the blowout Iorce efifective to distend the arcs occurring between cooperating contacts is directed toward a side wall of the arc chamber and efiectively away from the contacts enclosed by the arc chamber. This feature remains unaltered even though the polarity of the conductors or magnet is reversed. For best operation of a switch of this type it is essential that the are be directed to contact a closely adjacent side wall of the arc chamber to assist in extinguishing the arc and eiiectively away from the contacts enclosed by the arc chamber to avoid the formation of a single short circuiting arc between the two stationary contacts.

In the preferred form shown, the pair of stationary contacts l2 are spaced within each of the two restricted arc chambers l0 and cooperating therewith is a bridging contact member I! arranged to engage and disengage each pair of stationary contacts I2 for the purpose of making and breaking an electrical circuit therethrough. In order to provide blowout action and to obtain a. simple compact structure. a bar shaped permanent magnet 9 is placed symmetrically between each pairof contacts and spaced from and parallel to the plane of movement 01 both bridging contacts l3. The bar magnet 9 is also located so that the plane of movement of each bridging plane of the permanent magnet 9 and with the magnetic plane passing substantially through the points of contact of the switch. This position for the blowout magnet centrally located with respect to the four contact positions is unique in that blowout action for four contacts is secured from one magnet. The insertion of the magnet within a recess in the arc enclosure permits of the addition of a magnetic blowout without the usual increase in size of the switch.

In the switch structure disclosed the magnetic structures of the type disclosed can be more easily equipped with a magnetic blowout in the form oi a permanent magnet than the more cumbersome electromagnetic blowout. There are, however, switch structures in which an equivalent electromagnetic blowout can b incorporated that will utilize the inventive concept of this disclosure.

What I claim as my invention is:

1. In an electric switch comprising two spaced stationary contacts and a bridging contact member disposed in a single arc chamber with said bridging contact member arranged for movement in a given plane to cooperate with said stationary contacts to make and break an electric circuit therein, "the electric current to be controlled entering a stationary contact thence to the bridging contact and out through the other stationary con- 2,832,446 3 tact in a path substantially a U, the combination opening of contacts to be distended laterally of with said switch elements of a permanent magnet a line joining the stationary contacts. of bar shape having a north pole on on end 3. In an electric switch comprising four staand a south pole on the other end and positioned tionary contacts rectangularly spaced in one exteriorally and adjacent said are chamber with 5 p an ,t p e parallel bridging Contact e the longitudinal axis of said bar parallel to the bers each coope With a P Of a S plane of said motion of said bridging contact and y a s o a e a d b eak an electric cirwith each end of said bar adjacent a set or coopcuit therethrough, an enclosure to provide a seperating contacts to cause said arcs occurring on M a h mber for each set of stationary 11- opening of contacts to be distended laterally of tacts and its Cooperating d ng Co tact mema line joining the stationary contacts. her, the electric current to be controlled enter- 2, In an electric switch comprising two spaced ing the stationary contact, thence to its associstationary contacts and a bridging contact memat d bridging n a member, and t t h her disposed in a single arc chamb it i the associated stationary contact and through the bridging contact member arranged for movement 15 other Stationary Contacts d b d g Contact in a given plane to cooperate with said stationary member in like manner, the combination w contacts to make and break an electric circuit sa d l i swit h of a p rma nt ma n t f bar therein, the electric current to be controlled enshap p s t n d i the wall f sa d enclosure intering a stationary contact thence to the bridgtermediate said two chambers with its longitudiing contact and out through the other stationary I191 axis Parallel to the lines joining c o Said contact in a path substantially a U, the combinapairs of stationary contacts and said magnet or tion with said switch elements of a permanent such length to have each end adjacent a stationmagnet, three-pole type, of bar shape having like ary contact of each of said pairs, the magnetic poles at each end thereof and positioned exlines of said bar magnet to direct the arcs upon teriorally and adjacent said arc chamber with interruption of electric current flowing through the longitudinal axis of said bar parallel to the the contacts toward a wall of the enclosures and plane of said motion of said bridging contact and effectively away from the respective contacts.

with each end of. said bar adjacent a set of cooperating contacts to cause said arcs occurring on KONRAD HEINRICH. 

